If it is passed '--use-existing-bottest' it will run annotated in the existing directory instead of refetching it.
If it is passed '--use-existing-bottest' it will run annotated in the existing directory instead of refetching it.

BUG=
R=eernst@google.com

Review URL: https://codereview.chromium.org/1163783003

bwu-dart-contributing/reflectable,bwu-dart-contributing/reflectable,luisvt/reflectable,jakemac53/reflectable,jakemac53/reflectable,google/reflectable.dart,luisvt/reflectable,google/reflectable.dart